Originally Posted by Evil-Twin

I have clarified this questions hundreds of times over the last 15 years. AS most know I was intimately involved in the testing and application.
" THE LSX engine was not designed to use 87 Octane on a regular diet. in an effort to make it idiot proof we added the disclaimer that you could use 87 Octane to get you to a gas station that had premium fuel.. ( the idea was ) that the car would not blow up over a 30 mile trip to the next gas station. WE tried to make it idiot proof...
we did extensive testing and found that using reduced octane fuel caused internal damage over time to wrist pins, rings connecting rod and main bearings and specifically # 7 piston.

Every time you load the motor with 87 octane, step on the gas, shift gears then call for a load the engine will ping. this detonation before top dead center cause a double explosion.
1) when compression causes detonation ( not ENOUGH octane ) and then a second time when ignition spark fires. causing the rotating mass to prematurely fight the potential energy of the rotating mass. You would have to be plain stupid to allow your engine to detonate on a daily basis.

Pinging is the internal destruction of the rotating mass... over time this will cause engine damage to an engine that can easily see 400K. using 87 octane on a regular basis will cause loss of oil pressure over time and damage to the components I mentioned ..this was found in destructive and non destructive testing of the LSX motor design... WE did this testing because Dave wanted a 200,000 mile bench marked engine.. The first engine on the planet to be so certified.

Like I said, you would have to be an idiot to use 87 octane on a regular bases, unless you detuned the motor so much that the loss of power would be very noticeable. detune to prevent any detonation under any load.
Every time the engine pings in causes timing retard... "BUT>>>> the ping occurs first.. every time. Ping is internal destruction of the rotating mass. NO, the car does not stay in timing retard, once the load is off, the engine goes back to regular timing.. A LsX motor running on regular could see hundreds of individual pings on any given day. every time you demand more HP, to pass a car, go up a hill, make a turn and accelerate.

The sad thing about this is that I have posted thi8s hundreds of times over 15 years here.


Pretty hard to deal WITH STUPID ON A REGULAR BASIS,... BUT I TRIED FOR 15 YEARS.

Originally Posted by C5blk

Thank you Bill, the LS engine and the tuning is a whole new world to me. My hi-performance experience involved HEI ingnitions and carbs.

As stated in previous post, I cannot change how the owner before me treated the car all I can do is maintain it properly from here forward. Since the original post it has been getting a steady diet of 93 octane and I have put techron in the tank twice. It seems to run better but, it needs new plugs and wires, still has originals. That is a weekend project for cooler days.

A lot of good info here, without the information available here I would be completely lost! Thanks everyone!